The goal of this study is to incorporate nitric oxide (NO)-releasing compounds into polymer formulations that can be used to improve the biocompatibility of blood-contact surfaces in intravascular and extracorporeal devices. Previous studies have demonstrated that coating surfaces with polymer layers that continuously released small amounts of NO inhibited platelet activation and adhesion. Earlier materials had limited practical applications because they were not sufficiently stable to withstand manufacturing and storage, and because low NO capacity required prohibitively thick coatings. New NO donors have been developed that address these issues. The materials have significantly higher NO capacities; so more NO can be delivered with thinner coatings. These materials also have longer shelf life than their predecessors. Two NO donors will be used to form polymer coatings that can be applied to materials commonly used in cannulas, catheters, and extracorporeal blood treatment devices. Formulations will be devised to provide sufficient NO dose with the minimum possible coating material. The materials will be tested for their ability to withstand conditions typical in manufacturing, sterilization and storage. An animal model will be employed to evaluate biocompatibility and the ability of the materials to prevent platelet activation and adhesion.